Method of counterflow through a pump and method of controlling the operation of a pump in a pumping installation

• US 5,456,115 A
• Filed: 08/04/1993
• Issued: 10/10/1995
• Est. Priority Date: 11/28/1988
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd., Kansai Electric Power Company Incorporated
• Original Assignee: Hitachi, Ltd., Kansai Electric Power Company Incorporated
• Inventors: Yokoyama, Isao, Oono, Yasuteru, Kita, Ezo, Kuwabara, Takao, Nakagawa, Hiroto
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US08/102,041
• Time in Patent Office: 797 Days
• Field of Search: 73/659, 73/660, 73/168, 417/44 A, 417/45, 417/63, 417/44 B, 417/44 C, 417/44 D, 417/44 E, 417/44 F, 417/44 G, 417/44 H, 417/44 J, 417/44 R, 415/13, 415/26, 340/683
• US Class Current: 73/659
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04D 15/0027 Varying behaviour or the very pump F04D15/0055 and F04D29/46 take precedence
• CPC Class Codes: F04D 15/0066 by changing the speed, e.g. of the driving engine
• CPC Class Codes: F04D 15/0088 Testing machines
• CPC Class Codes: F04D 15/029 for pumps operating in parallel
• CPC Class Codes: Y02E 10/20 Hydro energy

Abstract

A method of detecting a counterflow in a pump comprises providing with detecting means for detecting variations in the discharge pressure of the pump and signal analyzing means for analyzing oscillation components contained in an output signal from the pressure detecting means, and detecting the pump'"'"'s operating point to have entered a counterflow characteristic operation region when a waveform of the detection signal generated in association with the variations in the discharge pressure of the pump exhibits a predetermined spectrum distribution. Further, when it is detected that the operating point enters a counterflow characteristic operation region, the escape from that region is performed by temporally throttling the guide vane and temporally increasing the rotating speed.

Claims

1. A method of detecting a counterflow in a pump, the method comprising the steps of:

providing a pressure detecting means for detecting pressure variations in a discharge pressure of the pump;

storing a frequency range of a first spectrum which is dominant while the pump is operating in a normal condition;

providing signal analyzing means for analyzing said pressure variations to detect a second spectra falling in a predetermined frequency band lower than the frequency range of the first spectrum; and

determining that the pump is operating in a counterflow condition when an amplitude of the second spectra is greater than a predetermined level.

2. A method of detecting a counterflow in a pump, the method comprising the steps of:

providing a detecting means for detecting mechanical vibrations occurring of the pump;

storing a frequency range of a first spectrum which is dominant while the pump is operating in a normal condition;

providing signal analyzing means for analyzing said mechanical vibrations to detect a second spectra falling in a predetermined frequency band lower than the frequency range in the first spectrum, and

determining whether the pump is operating in a counterflow condition when an amplitude of the second spectra is greater than a predetermined level.

3. A method of detecting counterflow conditions of a pump, the method comprising the steps of:

detecting a discharge pressure of the pump;

analyzing and evaluating the detected pressure in which an amplitude of spectra of the detected pressure within a predetermined frequency band which is less than the frequency of a dominant spectra in the normal operating condition is compared with a predetermined criteria level; and

judging an occurrence of a counterflow if a spectrum exists having an amplitude greater than a predetermined criteria level.

4. A method of detecting counterflow conditions of a pump, the method comprising the steps of:

detecting mechanical vibrations of the pump;

analyzing and evaluating the mechanical vibrations in which an amplitude of a spectra of the detected vibrations within a predetermined frequency band is less than the frequency of a dominant spectra in normal operating conditions as compared with a predetermined criteria level; and

judging an occurrence of a counterflow if there is a spectrum having an amplitude greater than the critical level.